Doctor of Philosophy, Case Western Reserve University, 2019, Macromolecular Science and Engineering

This work targeted to unveil the processing-structure-property relationships of four polymeric systems with diverse transport properties. The first and the second chapters concentrated on a through-pore membrane derived from polypropylene (PP) and polyamide 6 (Nylon 6) blends. The other three chapters discussed the adjustable gas barrier properties in regards to the morphologies of polymer blends and multilayer films. Among all the chapters, gas and liquid transport properties were proved as an effective identifier for the morphology. The change in transport phenomena was strongly correlated with the shift in the structure. In Chapter One and Chapter Two, porous membranes were produced from biaxial orientation of polymer blends comprising PP, Nylon 6, and polypropylene grafted maleic anhydride (PPgMA). During biaxial orientation, the continuous PP domains cavitated while the dispersed Nylon 6 domains remained rigid and spherical. The effect of blend composition on cavitation was analyzed and a ternary diagram generated to identify the composition range for through-pore formation. The membranes were found to have adjustable porosity up to 62% with nanoscale size pores. The membranes show very high filtration efficiency on separating 50 nm Latex microbeads from water suspensions. In Chapter Three, the compatibilization effect of linear low density polyethylene grafted maleic anhydride (LLDPEgMA) and high density polyethylene grafted maleic anhydride (HDPEgMA) on high density polyethylene (HDPE) /Nylon 6 blend system was investigated. HDPEgMA was identified as a better compatibilizer than LLDPEgMA for the HDPE/Nylon 6 blend system. In Chapter Four, multilayer films comprising polystyrene (PS)/polymethyl methacrylate (PMMA) and PS/polycaprolactone (PCL) alternating nanolayers with varied layer thickness were fabricated by multilayer coextrusion. The continuous layers started to break up into nanosheets and nanodroplets during the coextrusion process when the no (open full item for complete abstract)

Committee: Eric Baer (Committee Chair); Andrew Olah (Committee Member); David Schiraldi (Committee Member); Ya-Ting Liao (Committee Member) Subjects: Chemical Engineering; Materials Science; Packaging; Plastics; Polymers

Doctor of Philosophy, University of Akron, 2020, Polymer Science

Three-dimensional (3D) printing offers the unmatched ability to create medical devices with complex architectures matched to the patient's anatomy. However, most of the 3D printed devices are used clinically to create anatomical models, surgical guides and templates. The limited number of 3D printed implants being tested clinically are due to the lack of 3D printable synthetic biodegradable biomaterials with customizable physical and chemical properties, and the ability to interact and integrate with the physiological environment without invoking an adverse immune response. Herein, we present a library of one-component un-diluted polyesters with modular functionalities, which can be used to create customized 3D constructs using extrusion-based direct-write 3D printing (EDP). In the first part of the study, the side chain length of the polyesters is varied and its effect on the polymer rheology and 3D printability is investigated. The longer side chains increase the intermolecular packing length which allows the polyester to be extruded as continuous filaments at ambient temperatures. However, beyond a critical side chain length, the ordering of alkyl chains induces a semi-crystalline nature in the polymers which improves shape retention ability of the 3D printed filament. In the second part of the study, polyesters with various functional groups were synthesized and a hypothesis on their molecular structure was presented based on their linear rheology. The observed tangent delta transition at temperatures above their glass transition temperatures indicate the presence of a “secondary network” in the amorphous polyesters. Moreover, the supramolecular intermolecular interactions due to the functional groups improved the overall quality of the 3D printed construct. Finally, the application of the synthesized polyesters as drug delivery carriers is demonstrated and their preliminary biocompatibility was assessed by implanting them in vivo for six weeks which showe (open full item for complete abstract)

Committee: Abraham Joy (Advisor); Ali Dhinojwala (Committee Chair); Irada Isayeva (Committee Member); Mesfin Tsige (Committee Member); Ruel McKenzie (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Materials Science; Polymer Chemistry; Polymers

Doctor of Philosophy, Case Western Reserve University, 2019, Macromolecular Science and Engineering

This dissertation has a primary focus on design and development of composites by employing processing methods aimed at improving filler dispersion in polymers. Mixing elements taking advantage of extensional dominated flows are adopted. Several such mixing elements, extensional mixing elements (EMEs) to be specific, with varying degree of ability to impose extensional dominated flows, have been experimentally validated. A first attempt is made to enhance the dispersion of carbon black (CB), graphene nano platelets (GNP) and carbon nano tubes (CNT) in polypropylene (PP). Enhanced dispersion does translate into improved mechanical properties. A more comprehensive approach is adopted with an integrated computational and processing method on thermoplastic polyurethane (TPU) graphene oxide (GO) composites. The role of filler functionalization in exfoliation and TPU hard block crystallization is established. A difference in anisotropy and phase separation is observed between material processed with EME and kneading blocks. A significantly enhanced ductility is obtained by employing EME during processing. Improved abrasion and strength is also observed. A secondary focus of the thesis includes synthesis of composites by wet chemical and other processes to end up with composite materials with enhanced properties and/or improved material behavior. Hydrogels of poly(ethylene glycol) methyl ether methaycrylate filled with graphene oxide are made via a reversible assisted fragmentation termination (RAFT) approach. Reinforcement and lubrication effects are studied with the incorporation of covalent bonds between filler and matrix. Aerogels obtained from hydrogels of graphene oxide (GO) and montmorillonite (MMT) clay nanocomposites in poly(vinyl alcohol) are synthesized. Hence, obtained aerogels have improved compressive strength and further silylation makes them functional materials for oil-water separation. Twin-screw reactive extrusion of Thermoplastic polyureth (open full item for complete abstract)

Committee: Joao Maia (Advisor); Manas-Zloczower Ica (Committee Member); Dai Liming (Committee Member); Lewandowski John (Committee Member) Subjects: Analytical Chemistry; Chemistry; Design; Engineering; Materials Science; Nanoscience; Nanotechnology; Polymer Chemistry; Polymers

Master of Sciences (Engineering), Case Western Reserve University, 2018, Macromolecular Science and Engineering

Thermotropic Liquid Crystalline Polymers, which are materials made up of semi rigid rod-like molecules, have this unique property of orienting themselves during flow. This results in the formation of a very ordered melt phase which gives these materials a plethora of superior properties like high tensile modulus, good chemical resistance, very high thermal stability, flame retardant characteristics, dimensional stability etc. However, their cost prohibits their wide scale use and limits it to niche applications. This has engendered a lot of interest in the preparation of Thermoplastic/Liquid Crystal Polymer blends. Moreover, the fact that Liquid Crystal Polymers tend to reduce the melt viscosity, making the blend easier to process, is an added incentive in addition to their properties. Extension dominated flows have been long known to be more efficient in mixing as compared to shear dominated flows. Exploiting this concept, Carson and et al. at Case Western Reserve University have developed new mixing elements for the Twin Screw Extruder. These elements were proven to impart extensional forces as opposed to the shear forces imposed by the Kneading Blocks, resulting in better dispersive and dissipative mixing. This thesis aims to use these novel extensional mixing elements on a system of Polypropylene and Liquid Crystal Polymer compatibilized by a compatibilizer, to enhance mechanical and thermal properties of Polypropylene on addition of a low quantity of Liquid Crystal Polymer. Furthermore, this research also intends to compare the extensional mixing elements to the kneading blocks, which are the industry standard. All the extrusions were carried out on a co-rotating twin screw extruder, at two different temperatures of 285-295 °C and 220-230 °C. The purpose of using two different temperatures was to melt the Liquid Crystal Polymer to prepare blends in one case, whereas to keep it a solid and prepare composites in the other case.

Committee: João Maia (Advisor); David Schiraldi (Committee Member); Mike Hore (Committee Member) Subjects: Materials Science; Plastics; Polymer Chemistry; Polymers

Master of Science (M.S.), University of Dayton, 2014, Mechanical Engineering

Rigid-body shape changing mechanisms are a growing area of research due to their numerous practical uses. Rigid-body shape-change describes mechanisms comprised of rigid links connected with revolute and prismatic joints that are able to approximate a set of prescribed “morphing” curves. Planar rigid-body shape-changing mechanisms are synthesized to achieve different positions within a common plane. Designing for spatial tasks, however, is an area of emerging research. This thesis addresses topics in both planar and spatial shape-changing devices. First, a practical application for planar shape-changing devices is developed through the design and testing of variable geometry dies for polymer extrusion. Second, a synthesis methodology for spatial shape-changing is developed for serial chains of spherical four-bar mechanisms that can achieve specified helices. Variable geometry dies enable the extrusion of plastic parts with a varying cross-section. Extrusion accounts for 40% of all manufactured plastic parts due to its relatively low-cost and high-production-rate. Conventional polymer extrusion technology, however, is limited to fixed dies that produce continuous plastic products of constant cross section defined by the die exit profile. A shape-changing die allows the cross-section of the extruded part to change over its length, thereby introducing the capacity to manufacture plastic faster and with lower tooling costs than injection molding. This thesis discusses design guidelines that were developed for movable die features including revolute and prismatic joint details, land length, and the management of die leakage. To assess these guidelines, multiple dies have been designed and constructed to include an arbitrary four-sided exit profile where changes were made to the internal angles and length of sides as the extruder was operating. Experimental studies were conducted by using different extruder line settings and time between die movements. Test results ar (open full item for complete abstract)

Committee: Andrew Murray Ph.D. (Advisor); David Myszka Ph.D. (Advisor); David Perkins Ph.D. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, Case Western Reserve University, 2024, Macromolecular Science and Engineering

New processes and development of advanced technologies are essential for society to progress. The polymer field is vast and further expanding with the creation of new techniques and products. An advanced extrusion processing technique that has been beneficial in creating new products with very interesting properties takes the form of multi-layer co-extrusion. Initially multi-layer co-extrusion was and, in some cases, still is limited by the number of layers that can be achieved, the properties of different polymers can be combined to form products that are superior in different aspects due to the material selection. Layer multiplying co-extrusion was developed to achieve high layer numbers with the use of typically only two to three extruders. This work examines the layer multiplication technique capabilities for highly filled polymer layered systems and annular structures for pipe and blow molding applications. Limited work has been performed with filled polymer systems with using the layer multiplication technique. This work examines a model system to investigate effects of fillers at high loading levels on the stability of the layer structures created. The interface between filled and unfilled layers was examined xix to see the effect of particles at the interface. Along with this, particles with different rigidities were examined to investigate the effect of changing the rigidity of particles in confinement on the mechanical properties of the overall films. Previous work examined the creation of a tubing die for the layer multiplication technique to achieve high layer number annular structures. This work utilizes this tubing die to examine how angular rotation of the outer wall of the die land effects the weld line presence and pressure properties of the resultant tubes. The development of annular structures also allows for creation of blow molded structures. This work examines blow molding of high layer number bottles using a simple tabletop set-up and the (open full item for complete abstract)

Committee: João Maia (Committee Chair); Ica Manas-Zloczower (Committee Member); Gary Wnek (Committee Member); Alp Sehirlioglu (Committee Member) Subjects: Plastics

Doctor of Philosophy, Case Western Reserve University, 2022, Macromolecular Science and Engineering

Polymer processing is a fundamental key to achieve the desired properties to reach the needs of polymer applications. Thus, it is important to understand how the processing can contribute to material characteristics during the extrusion, while they are being processed. That is why this work propose a method able to perform analyses of the material while it is being processed during the extrusion: the on-line Fourier transform infrared (FTIR) spectroscopic system. The system consists of a device that was designed to be able to couple a commercial infrared spectrometer to an twin-screw extruder. On-line FTIR measurements can be done in different locations along the extruder barrel. Pearson VII function was used improving the linearity of mixture composition, which is proposed by Beer-Lambert's law, by around 14% when compared to the traditional methods. Polymer blends of polypropylene (PP) and polyamide 6 (PA6) at different weight composition ratio were used to validate the on-line system during extrusion. The area ratio between the IR bands at 1640 cm-1 (υC=O) and 1373 cm-1 (σC-H3) were measured on-line for all the blend compositions and shown to be in good agreement with off-line measurements. When the reactive blending of polyamide 6 (PA6) and polypropylene grafted with acrylic acid (PP-g-AA) (in blends of 80%/20% and 30/70% of PP-g-AA and PA6, respectively) was investigated along the extruder length, a increase of the IR band area ratio (1640/1373 cm-1) was achieved when the process condition aggressiveness in mixing was improved due to the generation of fresh interface between the two phases, as it is shown through scanning electron microscopy (SEM). Trough on-line FTIR measurements it was possible to visualize the development of the reactive blending reaction of PP-g-AA/PA6 blends inside the extruder. For example, different process conditions lead to the same or different amount of reaction (IR area ratio 1640/1373 cm-1) at the end of the extruder, but they fo (open full item for complete abstract)

Committee: Joao Maia (Advisor); Joao Maia (Committee Chair); Sebastiao V. Canevarolo (Committee Member); Gary E. Wnek (Committee Member); Jennifer L. W. Carter (Committee Member); Hatsuo Ishida (Committee Member); Leonardo Canto (Committee Member) Subjects: Engineering; Materials Science; Plastics; Polymers

Doctor of Philosophy, The Ohio State University, 1987, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, University of Akron, 0, Polymer Engineering

The dispersion of nanofillers in polymers has been the biggest challenge in exploiting the full use of the nanocomposites. The purpose of the present study is to investigate the effect of ultrasonically aided extrusion in improving the dispersion of various nanofillers in the polymer composites. In the study, polyetherimide (PEI)/graphite, polypropylene (PP)/carbon black (CB), PP/carbon nanotube (CNT) and PP/graphene nanoplatelet (GNP) composites were prepared using a twin screw extrusion without and with imposition of ultrasonic waves. Three different screw configurations were designed to study the efficiency of ultrasonic treatment in the extrusion. Two compounding methods were utilized in preparing the PP/CNT composites. One is the direct compounding (DC) method and the other one is the masterbatch dilution (MD) method. The efficiency of nanofiller dispersion in these two methods was compared. Four kinds of PP of different molecular weight and molecular weight distribution were used in preparation of PP/CNT composites. The mechanism of ultrasonic cavitation was also investigated. The rheological, mechanical, thermal and electrical properties and morphology of all the PP composites were systematically studied to elucidate the processing-structure-properties relationship. The simulation of the nonlinear rheological behavior of PP/CNT composites was carried out. The results showed that the ultrasonic treatment is more efficient in improving the dispersion of expanded graphite (EG), CNT and CB than GNP and original graphite in polymer matrix. Among the three screw designs, the dispersion of nanofillers in polymer was found to be more related to the presence of kneading elements than the reverse elements and residence time. At higher pressure in the ultrasonic zone, the degradation of PP was less severe than at lower pressure. The ultrasonic treatment had a more prominent effect in improving the dispersion in the MD method than in the DC method. In the MD method, t (open full item for complete abstract)

Committee: Avraam Isayev Dr. (Advisor) Subjects: Plastics; Polymers

Doctor of Philosophy, Case Western Reserve University, 2016, Macromolecular Science and Engineering

CHAPTER1: A synthetic polymeric lens was designed and fabricated based on a bio-inspired, “Age=5” human eye lens design by utilizing a nanolayered polymer film-based technique. The internal refractive index distribution of an anterior and posterior GRIN lens were characterized and confirmed against design by µATR-FTIR. 3D surface topography of the fabricated aspheric anterior and posterior lenses was measured by placido-cone topography and exhibited confirmation of the desired aspheric surface shape. Furthermore, the wavefronts of aspheric posterior GRIN and PMMA lenses were measured and simulated by interferometry and Zemax software, respectively. Their results show that the gradient index distribution reduces the overall wavefront error as compared a homogenous PMMA lens of an identical geometry. Finally, the anterior and posterior GRIN lenses were assembled into a bio-inspired GRIN human eye lens through which a clear imaging was possible. CHAPTER 2: A nanolayered polymer films approach to designing and fabricating gradient refractive index lens (GRIN) lenses with designer refractive index distribution profiles and an independently prescribed lens surface geometry has been demonstrated to produce a new class of gradient index optics. This approach utilized nanolayered polymer composite materials from polymethylmethacrylate (PMMA) and a styrene-co-acrylonitrile copolymer (SAN) with a tailorable refractive index intermediate to bulk materials to fabricate discrete gradient refractive index profile materials. A process to fabricate nanolayered polymer GRIN optics from these materials through thermoforming and finishing steps is also described. A review of a collection of technology-demonstrating nanolayered GRIN case studies is which include: optical performance of an f/# 2.25 spherical GRIN plano-convex singlet 1/10 the weight of a similar BK7 lens and a bio-inspired aspheric human eye lens. Original research on the fabrication and characterization of a Lunebu (open full item for complete abstract)

Committee: Eric Baer Prof. (Committee Chair); Alexander Jamieson Prof. (Committee Member); Andrew Olah Dr. (Committee Member); Donald Schuele Prof. (Committee Member) Subjects: Polymers

Master of Science in Electrical Engineering, Cleveland State University, 2013, Fenn College of Engineering

The interesting background and history of polymer extrusion are first introduced in this thesis. The complexity of the extrusion process is described, along with sources of disturbances. A literature review of the types of controllers that have been used for viscosity regulation in polymer extrusion is given, including the proportional-integral-derivative (PID) proportional-integral (PI) controllers. Polymer viscosity in extrusion is difficult to model accurately and its regulation is prone to disturbances. Active Disturbance Rejection Control (ADRC) is the right method for addressing the model inaccuracies and facilitates a straightforward solution to accommodate industrial needs with parameters that can be easily tuned by the operator. To do this, first the problem of viscosity regulation has to be reformulated as a disturbance rejection problem. This thesis demonstrates, using a circuit and simulation, an advanced solution. The initial results are encouraging, showing better control than PI.

Committee: Zhiqiang Gao PhD (Committee Chair); Lili Dong PhD (Committee Member); Orhan Talu PhD (Committee Member) Subjects: Electrical Engineering; Polymers

Master of Science (MS), Ohio University, 1982, Chemical Engineering (Engineering)

The primary objective of this investigation is to determine the transparency of Teflon ®100 ribbon extrudates produced by the fixed boundary extrusion orientation crystallization (FBEOC) process to solar radiation. A Perkin-Elmer 330 uv-visible spectrophotometer was employed to measure the light transmitting property of the polymer-samples. The spectrophotometer was interfaced with a HP-1000 minicomputer for efficient data processing. Results of the characterization tests performed indicate that transparency of the polymer can be significantly improved by improving the physical properties of the polymer by extrusion. However, some of the samples showed variation from the above, presumably, due to the effect of surface roughness etc. Thickness of the polymer ribbons have been found to show significant effect on the transparency.

Committee: John Collier (Advisor) Subjects: Engineering, Chemical

Doctor of Philosophy (PhD), Ohio University, 1992, Electrical Engineering & Computer Science (Engineering and Technology)

Since great emphasis is being placed on the material processing research in the department of defense, other government research agencies, and industries; currently, extensive research needs to be conducted in this field. Design and analysis programs for metal processing are well developed and easily available. However, the design and analysis of flows in extrusion dies for polymer processing has not been fully explored. One of the reason is lack of good three dimensional analysis programs for flows of such fluids and the die design methodology for it. The objective of this research was to develop a finite element methodology, formulate and program the finite element equations to model three dimensional flows of non-Newtonian fluids inside an extrusion die. The weighted residual technique with Galerkin criterion was used as the means of formulating the finite element equations. The weighted residuals method is a technique for obtaining approximate solutions to linear and non-linear differential equations. The power law constitutive model was used to update the non-linear viscosity. Extrusion is a complicated process, and polymeric fluids, because of their non-linear characteristics, compounds its effects. The extrusion die is the heart of the process. Die design is very critical for obtaining a better product. The die design package was modified to design streamlined dies for fiber spinning, co- extrusion, and thin film extrusion. A finite element program was developed to calculate the velocities and pressure for flows in three dimensional geometries using the power law model. The power law equation for viscosity calculation is one of the most well known and widely used empiricism in the polymer processing industry. The power law model provides a good estimate of the effects of the non-Newtonian viscosity in polymeric flows. It can describe the viscosity for a wide range of shear rates but cannot predict memory effects which exist in some polymer flows. Three test c (open full item for complete abstract)

Committee: J. Gunasekera (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2004, Macromolecular Science

Mixing is an important component in most processing operations including but not limited to polymer processing. Generically, mixing refers to a process that reduces composition nonuniformity. Since the entropy is the rigorous measure of disorder or system homogeneity, in this work we will explore various ways to employ the entropy to characterize the state of mixing in a multi-component system. The various species can be initially present in the system or they can evolve as a result of a dispersive mixing operation involving a cohesive minor component. Computer simulation of agglomerate dispersion and sequential distribution of all particles obtained in the system allows us to evaluate the overall mixing efficiency of processing equipment. Evaluation is based on a specific mixing index, calculated using the Shannon entropies for different size fractions. The index can be tailored to give preference to different particle size distributions, thus relating the quality of mixing to specific properties of the final product. We propose a Shannon entropy based index of color homogeneity to assess color homogeneity as well as deviations from a standard/ideal color. We illustrate the concept by analyzing ABS polymeric samples obtained in a single screw extruder by mixing blue and yellow polymer pellets. Alternatively the proposed technique can be employed to assess the efficiency and degree of distributive mixing attained in polymer processing equipment. We present numerical simulations for an ABS resin extrusion in an industrial conventional single screw extruder. Based upon the flow field patterns obtained in the simulations, a particle tracking procedure was employed to obtain information about the spatial distribution of particle tracers of two colors. Results of the simulation were compared with experimental data obtained under similar extrusion conditions. To evaluate the degree of color mixing and color homogeneity for the system, we also employ the entropy based inde (open full item for complete abstract)

Committee: Ica Manas-Zloczower (Advisor) Subjects: Plastics Technology